Field of the Invention
The invention relates to an optical device and a projector, and particularly relates to a wavelength conversion device and a projector using the same.
Description of Related Art
In recent years, projectors using a solid-state light source such as light-emitting diodes (LED) and laser diodes, etc., gradually occupy a place in the market. Light-emitting efficiency of the laser diode is about 20% higher than that of the LED. In order to break through a light source limitation of the LED, a pure color light source required by the projectors that is produced by exciting a phosphor powder by a laser light source is gradually developed. Moreover, a laser projector uses a laser light beam provided by the laser diode to excite the phosphor powder to emit light to serve as an illumination light source of the projector, so as to achieve various brightness requirements of the projector. Therefore, the projectors adopting a laser light source device to serve as an illumination system have a great potential to replace the conventional high pressure mercury lamp to become the light source used in the new generation mainstream projectors.
In a current laser projector, a reflective layer is generally formed on a metal substrate through a film coating manner. A phosphor layer is coated on the reflective layer to construct a phosphor wheel, and then the laser light beam emitted by the laser light source device excites the phosphor layer of the phosphor wheel on the metal substrate to produce light beams in different colors (for example, a green light beam and a yellow light beam). The laser light beam (for example, a blue light) may directly pass through a hollow slot or a transparent diffusion plate on the metal substrate of the phosphor wheel to combine with the excited light beams for producing light beams in various colors. However, the reflective layer generally has a same coating design and cannot achieve a high reflectance for all kinds of color light beams, and in order to make the reflective layer to be adapted to reflect different color light beams, multilayer coating has to be adopted, which increases a manufacturing cost. Moreover, flatness and a coating matching ability of the metal substrate are relatively poor, which results in a fact that the reflectance of the reflective layer is hard to be increased.
The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art.